Process of and apparatus for amalgamating and separating metals



April 13, 1937. -w KROLL 2,077,332

PROCESS OF AND APPARATUS FOR AMALGAMATING AND SEPARATING METALS FiledFeb. 19, 1934 s Sheets-Sheet 1 E Q 6 N 1 I \11 W on a: N 2 I a E I O [WIll Mai-fin 100, .BY

ATTORNEYs P" 1937. M. w. KROLL PROCESS OF AND APPARATUS FOR AMALGAMATINGAND SEPARATING METALS Filed Feb. 19, 1934 3 Sheets-Sheet 2 ATTORNEYSApril 1937. M. w. KROLL 7,332

PROCESS OF AND APPARATUS FOR AMALGAMATING AND SEPARATING METALS FiledFeb. 19, 1934 3 Sheets-Sheet 3 ZZ, INVEIQTOR ATTO RNEYS ammo armscrim-Anna mars w. Kroll. 1mm. Application February 19, Serial a.112,026 a mm; (or. flit-1.5)-

The invention relatesto a process of and apparatus for, amalgamating andseparating metals.

The primary aimof the present invention is to providea process of andapparatus of this char- 5 acter wherein in their use for the purpose ofextracting metals from finely ground ore, they.will

enable the finely ground ore to mu; with'the solution in the properratio to keep the mass in a fluid or liquid state and the resultant pulpcomprising the pulverized ore and solution will be sustained in a stateof agitation so that all ore particles will be suspended tov theextentthat no settling will occur at the bottom of the vat, the rate ofagitatiori being, of course, varied in ac-' cordance with the specificgravity of the material under treatment.

Another object of the invention is the provision of a process of andapparatus of the kind specified, wherein the agitation which'is neces- 0sary to keep the mineralv particles in the solution suspended may beproduced by utilizing a down-draft propeller, mechanically 'driven atthe properfspeed, and in some instances, it may be found necessary or.beneficial to utilize the "propeller for disintegration of material,this being 1 had by perforating the propeller blades. The disintegrationaction is found especially beneficial in freeing extremely fine goldfrom clay, the.

action of the propeller producing a constantly moving stream of materialwith a downward motion, while itis also possible to utilize an electriccurrent of the properv'oltag'e, current density and frequency for "theproduction of electrical precipitation, separation or amalgamation ofthe. metallic particles-while. suspended and under agitation, theseparticles being deposited on acathode or electrical-conductor platedisposed, in the bottom!!! a-vat and of such material or composition asto produce the desired result in connection with the mineral undertreatment.

- A further object of the invention is the pro vision of a process ofand apparatus for amal gamating' or"extracting ores or metals, whereinthe solution used in connection with the ore under 45 treatment be ofsuch a chemical nature as to produce -a-condition which will aid inbringing ,4

about extraction-of the desired metals and the electrical resistance ofthe solution controlled by the addition of salts, acid or alkali in thecorrect 5o proportions tobring abouts desired 'state of conductivitydnthe solution and also that will, in many instances, produce chemicalchangesin the material undertreatment so 'tnatthe timeiof 7 treatment,the cost of electric current, andthe as percentage of abstractionobtainable canbe made more favorable. In some instances, theuse of achemical reagent makesit possible to so change the chemical compositionof the material under treatment that although "it may be partially orentirely refractory in its original state, the al 5 teration in thenature of the material will en'- able the same to yieldto the process.

In the accompanying drawings:

Figure 'l' is a sideelevation of the apparatus constructed in conformitywith the invention and employed in carrying out the process ofamalgamation and separation of ores. 1 1 Figure 2 is a verticallongitudinal sectional view thereof.

Figure 3 is a vertical transverse sectional view 15 taken on the line3-3 of Figure '2 looking in the direction of the arrows.

Figure 4 is a view similarto Figure 3 showing a slight modification ofthe apparatus. 1

Similar reference characters indicate corresponding parts throughout theseveral views in 20 the drawings.

Referring to the drawings in detail, particu; larly Figures 1' to 3inclusive, the apparatu s for the amalgamation and separation of ores,as constructed in conformity with the present invention, comprises asubstantially V-shaped agitatingvat- A which includes the oppositevertically disposed spaced parallel sidewalls L5, these being joined inany suitable manner with upwardly 3o divergentspaced end walls 6 for ahopper iormation of the vat. Beneath the said vat is a combined settlingand filtering vat I, the same beingdl videdat an intermediate point by avertical partition 8 to provide the settling chamber 9 and the filteringchamber 10, respectively', the partition being formed with a filteringscreen ll.

of any approved construction, 80 that the liquid or fluid passing fromone chamber to other filterli,.aswillbe obvious. ,r

Risingfrom the vat l 'at one side of the vat A' a will be subjected tothe filtering action of the 40 are suitable supports lrfor a platform ISon which is arranged a pump ll of the motor or hand driven type havingthe lift pipe or cylinder li-which-extends'withinthe chamber 9, so thatits contents can be retumedZto the vat A, the'delivery of the liquidfrom the pump 14 into the vat A being had throughthe discharge spout I.

of saidpump ll. l 5 Mounted in suitable bearings ll arranged near thetop of the vat A, at one end thereof, is the shaft it of anagitator'naving the propeller blades 1! of'the'form t'o effect'a downdraft within the said vat A, theshaft I! of theagitatou: Mini disposedat the same inclination of the end walls 6 of the vat A next thereto.Suitably supported upon the vat A is an electric motor 20 which,

through the pulleys 2| .'and belt 22, respectively, has connection withthe shaft l8 of the agitator so that the latter'will be driven directlyfrom curialcolumn of the cathode 23 being indicated at 29 within the vatA. i

In the process for the extraction of metals by electrical amalgamationand separation, the apparatus is employed and for the purpose ofextracting metals from finely ground ore, the finely ground ore is mixedwith a solution in the proper ratio to keep the mass in a fluid orliquid state 2 and such ore and the solution is admitted into the vat Aso that the pulp comprising the pul-' verized ore and solution will bemixed and kept in a state of agitation by the agitator, whereby all oreparticles will be maintained in'suspension to the extent that nosettling will occur at the bottom of the vat A. Of course,the rate ofagitation is varied in conformity with the specific gravity oi thematerial under treatment and such agitation is essential. to keep themineral particles in the solution suspended,"the agitation being in adownward direction, the propeller blades l9 being located beneath the,level, of the solution or the mixture as contained within the vat A andthe agitator producing a constantly 40 moving stream of material with adownward mo tion so as -to bring about an intimate contact of f allparticles suspended-with the bottom of the vat.

By using the down draft, force of gravity is utilizedv in helping tobring all particles sus-' pended in contact with the bottom oi the vat Aand in combination therewith it is possible to. use electric current toassure electrical precipitation, separation or amalgamation of themetallic particles suspended in the vat A at the time or I agitation andto deposit these mineral particles on the cathode located at-thelowermost point of the vat A. The anode 28 for conducting the electriccurrent is so placed in the vat that the exposed area in contact bevaried to meet specific requirements. Furthermore, the distance of airgap between the anode and the cathode maybe varied by the adjustablemembers 30 for regulating current density, and the material comprisingthe anode and the cathode is to be of a composition which will preventexcessive disintegration of the anode, the cathode material beingdetermined by the material to be treated. a

within the vatA is controlled by the additioifof salts, acid or alkaliesin the correct proportions to'bring about a desired state ofconductivity in the solution, as well as in many instances to pro-'zo-iiuce chemical changes in the material under treatment, so that thetime of treatment, the

costof electrical current e action obtainable can be made morefavorable. j .It is also possible to bring about-a complete with thesolution may' The electrical resistance of the solution as used and thepercentage of extraction of the desired metal. from a continuous fiowthrough the vat by the use of. a chemical reagent, the incoming feed ofpulp to the vat A and the discharge rate being regulated in accordancewith the time required for satisfactory extraction from the materialunder treatment.

In one side wall 5 of the vat A is arranged a gate valve ill, the samebeing disposed approximately one foot above the extreme bottom ofthesaid vat and this valve being utilized to facilitate discharging thepulp after satisfactory extraction of the metals in the material undertreatment. The material in the vat A is kept in a state of agitationduring the period of time requiredfor discharging the tailings and thefresh solution being pumped into the topof the vat at the samerate thatthe solution is drained off through the discharge valve 3|, the pump Hbeing actuated to deliver the fresh solution into the vat A. The valve 3l'has connected thereto a flexible pipe 32 for the discharge from thevat A to be conveyedjnto the settling chamber Ill and through theinstrumentality of the filter II the liquid contained in the tailingsfrom the valve 3] will be admitted to the chamber 9 of the vat 1, while'the ore carried in suspension by the liquid will be deposited in thechamber it, it being-apparent that thesolution when passed through thescreen II will be reconditioned to bring it back to a clarified state tobe used again in the agitating vat A. The exhausted ore after having.been treated for extraction is removed from the settling vat in anysuitable manner, preferably by the use of -a sand pump (not. shown) orby any other mechanical means which excludes the removal of the liquidreagent, thus confining the loss of reagent to that which is carried outin the form of a moisture contained in the pulp.

By reason of the formation of the propeller blades IQ of the agitator,when the same is in operation, a suction is created above the positionof such blades which has a tendency to sink all mineral particles whichmight have otherwise a tendency to fioat on the surface of the solutiondue to the surface tension of the solution used.

The angle of the shaft i8 of the agitator with relation to the angle ofthe vat is such as to create a downward movement of the solution on theside of the vat where the propeller shaft is located and an outwardmotion of the solution in the opposite side of the vat, -thus keepingthe.

solution-with its suspended material in a rapid state of circulation inthe vat A in order that the cathode in the bottom of thevat will becontinuously bombarded with the mineral particles which tion.

Included in the electric circuit for the cathode and'a'node is anammeter 33 and a rheostat 34, respectively, these being mounted directlyvat A, thus making it possible to measure and control the currentdensity used in the extraction process.

It is, of course, understood that the chemical reagents, as well as theelectric currents, used with the apparatus'in amalgamation andseparation by the process are many and must be changed in order to bringabout a satisfactory extraction of the desired metal or metals from eachspecific type or variety. of ore of which its chemical or mechanicalstructure may warrant and the principles of using chemical reagents areto make the suspended solution in the vat an elec-' trolyte, so that thenietals in the solution will assume a positive electrical charge fromthe anode on the are in a state'of suspension in such solu-. 7

and thus be passed to the cathode or to bring about a complete orpartial ,chmical change in the ore under treatment, or to dissolvepartially or completely the metals and converfthem into.

5 soluble electrolyte-salts so that they may be precipitated at thecathode by the electrical current, or to dissolve undesirable metals andmake them non-electrolytes so that they will not interfere with thecompletion of the process. The specific 1o reagents for the leaching ofthe metals and the formation of electrolyte saltsthat they may beprecipitated at the cathode by the electric current may be potassiumhydroxide; potassium chloride; ammonium hydroxide; sulphuric acid;

hydrochloric acid; nitric acid; potassium nitrate or sodium nitrate;potassium bichromate; cyanide potassium or potassium sodium and calcium;

- barium hydroxide; calcium hydroxide and potassium carbonate or calciumcarbonate or sodium carbonate.

A reagent may be used to counteract an undesirable' condition existingin'the ore, such as a strong acidity or alkalinity that maybeunfavorable and by the addition of a counteractor bring about thedesired condition forthe extraction of the metal or metals. This reagentshould be called a sizer or conditioner which could be used as anelectrolyte or just bring the ore pulp to a neutral condition and theaddition of a beneficial 3 reagent to bring the conductivity of thesolution to the desired point.

In Figure 4 of the drawings there is shown a slight modification of theapparatus wherein the vat B, at its lower point,'has fitted therein anauger 35 having the extended shaft 36 for attachment to a mechanicaldrive for the rotation thereof and this auger is used for the discharge.of concentrates or mercury as may be within the lowermost portion ofthe vat B, in event that the vat is used .as a continuous typeconcentrator, as will be clearly apparent, the auger housing 31 beingformed with a downwardly directed discharge spout 38 for communicationwith the lowermost vat of the said apparatus.

The V shape of the vat utilized in the process has an important bearingnot only upon the recovery of desired mineral but also from a standpointof discharging tailings. The position of the propeller with its downwardmotion creates a circulation of the mass or material under treatment onthe side that the propeller is located and an upward movement on theopposite slope. It will be noted that the tailings discharge outlet islocated in the approximate center of this circulating mass of material.This is very important where mercury is being used as a cathode becauseif the discharge outlet were located in the propeller slip stream, therewould be a tendency to carry over mercury in the discharged tailings.

Another important feature is the fact that in an ore that carriesmineral in a finely divided state, it is absolutely essential to havethis circulating action of the entire mass under treatment to preventaccidentalflotation of the mineral particles on the surface of thesolution in use in the vat. So it becomes'quite evident from the abovethat the particular shape of the vat is quite important a so far as theentire process is concerned.

What is claimed is: I An apparatus of the kind described comprising adownwardly tapered vat closed at its lowermost smaller end and open atits top for' receiving comminuted ore and a solution, bearings fixed tothe side wall of said vat at the open top thereof, a. rotatable shaftjournaled in said bearings in close parallel relation to the side wallof said vat and having an agitator head located close to the bottom endof the vat to be deeply submerged in thesolution therein for causing-acontinuous unrestricted down flow of the solution in the direc tion ofthe lowermost end of saidvat and a circulation in an upward direction atthe side of the vat remote from said head, atray beneath the vat andhaving a vertical partition dividing it into independent compartments,9. screen asso-- ciated with the partition at the upper edge of thelatter, a pump operating in one of the compartments for'transi'erringsubstance therefrom into the vat, a mercurial pocket formed at thelowermost end of the vat and containing mercury, a drain-from 'saidpocket, .an anode fixed to the side of the vat interiorly thereof andremoved from the level of the mercury in the pocket, and

a lead from the vat to the other compartment and positive and negativecurrent leads to a direct current supply from said mercury and saidanode.

MARTIN W. KROLL.

